In the past, beer kegs were wooden barrels with stoppers and the beer was released simply using gravity and air. Today, kegs are sterile stainless steel containers and inert pure gases are used to drive beer out of the keg using a keg tap.
A keg coupler is a key element of any draft beer system; it's a small yet vital piece of equipment that connects the gas and beer lines. There are six different keg tap systems, making it very important to check and cross reference your purchases when shopping for kegs, couples, and pumps to ensure that they will work well together. You might wonder why there are six different keg tap systems instead of one universal keg tap. Although it adds complexity to the beer keg and tap world, the variety of keg tap systems allow for easier separation of kegs once they are empty. Besides the markings on the keg, different keg taps help to identify a brewery’s cooperage (kegs) so they are properly returned for re-filling.